Help a n00b with Skeinforge please!

Hi there,
I am new to this whole 3D printer stuff, and I am enjoying learning and doing lots of reading!
however there is one thing I cannot seem to find a solution to my problem:

I am running replicatorg 0040, and after downloading STL's from somewhere like Thingiverse, I click "generate code" using default settings.
It runs through the process of slicing up the model, and then instead of allowing me to print, it opens up an page which shows me the route the extruder would take.
I then close that page and then try to print and then the printer starts up and then finished within 14 seconds.

This is seeming to happen more and more...
I have tried running the model through something like modelRepairService, in case there is something wrong with the model, but get the same problem.
After looking through the output there does not seem to be any errors....